Injection molding flow control apparatus and method

ABSTRACT

An apparatus for controlling the rate of flow of mold material to a mold cavity, including a valve system in fluid communication with an actuator to drive the actuator at one or more rates of travel, the valve system having a start position, one or more intermediate drive rate positions and a high drive rate position, the start position holding the valve pin in a gate closed position; a controller that instructs the valve system to move from the start position to the one or more intermediate drive rate positions and to remain in the one or more intermediate drive rate positions for one or more corresponding predetermined amounts of time and further drives the valve system to move from the one or more intermediate drive rate positions to the high drive rate position on expiration of the one or more predetermined amounts of time.

RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityto PCT/US11/62096 filed Nov. 23, 2011, which claims the benefit ofpriority to U.S. Provisional Application Ser. No. 61/475,340 filed Apr.14, 2011 and to U.S. Provisional Application Ser. No. 61/416,583 filedNov. 23, 2010, the disclosures of all of the foregoing of which areincorporated by reference herein in their entirety as if fully set forthherein.

The disclosures of all of the following are incorporated by reference intheir entirety as if fully set forth herein: U.S. Pat. No. 5,894,025,U.S. Pat. No. 6,062,840, U.S. Pat. No. 6,294,122, U.S. Pat. No.6,309,208, U.S. Pat. No. 6,287,107, U.S. Pat. No. 6,343,921, U.S. Pat.No. 6,343,922, U.S. Pat. No. 6,254,377, U.S. Pat. No. 6,261,075, U.S.Pat. No. 6,361,300 (7006), U.S. Pat. No. 6,419,870, U.S. Pat. No.6,464,909 (7031), U.S. Pat. No. 6,599,116, U.S. Pat. No. 7,234,929(7075US1), U.S. Pat. No. 7,419,625 (7075US2), U.S. Pat. No. 7,569,169(7075US3), U.S. patent application Ser. No. 10/214,118, filed Aug. 8,2002 (7006), U.S. Pat. No. 7,029,268 (7077US1), U.S. Pat. No. 7,270,537(7077US2), U.S. Pat. No. 7,597,828 (7077US3), U.S. patent applicationSer. No. 09/699,856 filed Oct. 30, 2000 (7056), U.S. patent applicationSer. No. 10/269,927 filed Oct. 11, 2002 (7031), U.S. application Ser.No. 09/503,832 filed Feb. 15, 2000 (7053), U.S. application Ser. No.09/656,846 filed Sep. 7, 2000 (7060), U.S. application Ser. No.10/006,504 filed Dec. 3, 2001, (7068) and U.S. application Ser. No.10/101,278 filed Mar. 19, 2002 (7070).

BACKGROUND OF THE INVENTION

Injection molding systems have been developed having flow controlmechanisms that control the movement of a valve pin over the course ofan injection cycle to cause the pin to move either upstream ordownstream over the course of an injection cycle in order to raise orlower the rate of flow of fluid material into the cavity to correspondto a predetermined profile of fluid flow rates over the length of theinjection cycle. A sensor is used to sense a condition of the fluidmaterial or of the apparatus, the sensor sending a signal indicative ofthe sensed condition to a program contained in a controller that usesthe signal as a variable to control movement of the valve pin inaccordance with the predetermined profile.

SUMMARY OF THE INVENTION

In accordance with the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

an injection molding machine and a manifold that receives an injectedmold material from the injection molding machine, the manifold having adelivery channel that delivers the mold material under an injectionpressure to a first gate of a mold cavity,

an actuator interconnected to a valve pin driving the valve pin from afirst position where the tip end of the valve pin obstructs the gate toprevent the injection fluid material from flowing into the cavity,upstream to a second position upstream of the gate where the moldmaterial flows at a maximum rate through the gate and continuouslyupstream from the start position through one or more intermediatepositions between the first position and the second position wherein thetip end of the valve pin restricts flow of the injection mold materialto one or more rates less than the maximum rate,

a valve system for controllably driving the valve pin, the valve systembeing controllably movable from a start position to one or moreintermediate drive rate positions and a high drive rate position, thehigh drive rate position driving the pin upstream at a high rate oftravel, the intermediate drive rate positions driving the pin upstreamat one or more intermediate rates of travel that are less than the highrate of travel,

the method comprising;

selecting one or more lengths of time for the valve system to operate orreside in corresponding ones of the one or more intermediate drive ratepositions,

beginning an injection cycle with the tip end of the valve pin in thefirst position and the valve system in the start position,

adjusting the valve system to operate at the one or more of theintermediate drive rate positions for the one or more selected lengthsof time to drive the valve pin continuously upstream,

-   -   adjusting the valve system to operate at the high drive rate        position to drive the tip end of the valve pin continuously        upstream at the high rate of travel upon expiration of the one        or more selected lengths of time.

In an alternative embodiment, the method and apparatus can carry out asingle adjustment of the valve system or velocity to cause the valve pinto travel at a less than maximum velocity during the entirety of theinjection cycle all the way from the gate closed position to the maximumend of stroke position.

The valve system is typically adjusted to operate at the one or moreintermediate drive rate positions after the mold material has beeninjected into the cavity through another gate and has travelled throughthe cavity past the first gate. The valve system can be adjusted tooperate at a single intermediate drive rate position for a singleselected length of time.

The valve system is typically interconnected to an electrical signalgenerating device operable to generate electrical signals ofcontrollably variable output, the valve system being adjustable in driverate position to increase the flow of drive fluid to a degree that isproportional to the degree of output of the electrical signals, thesteps of adjusting the valve system comprising operating the electricalsignal generating device to generate electrical signals that adjust thedrive rate positions of the valve system according electrical signals ofselected degree of output.

Each of the drive rate positions of the valve system preferably have adegree of openness, the drive fluid of the valve system driving theactuator and the valve pin at a rate that is proportional to the degreeof openness of the positions of the valve system, the one or moreintermediate drive rate positions having a degree of openness that isless than the degree of openness of the high drive rate flow position.

The length of travel between the first position and the one or moreintermediate positions along the drive path is typically between about 1mm and about 5 mm.

In another embodiment of the invention there is provided an apparatusfor controlling the rate of flow of mold material to a mold cavity, theapparatus comprising:

an injection molding machine and a manifold that receives the injectedmold material from the machine, the manifold having a delivery channelthat delivers the mold material at one or more flow rates through a gateto the mold cavity,

an actuator interconnected to a valve pin having a tip end, the actuatorbeing drivable to move the valve pin along a path of travel startingfrom a downstream gate closed position continuously upstream to andthrough a series of successively upstream intermediate upstream gateopen positions and further continuously upstream to a high upstream gateopen position,

a valve system in fluid communication with the actuator to drive theactuator with drive fluid at one or more rates of travel, the valvesystem having a start position, one or more intermediate drive ratepositions and a high drive rate position, the start position holding thevalve pin in the gate closed position, the high drive rate positiondriving the actuator upstream at a maximum velocity under which thevalve system is capable of driving the actuator, the one or moreintermediate drive rate positions driving the actuator upstream at oneor more corresponding velocities that are less than the maximumvelocity,

a controller interconnected to the valve system, the controller beingadapted to control movement of the valve system between the startposition, the one or more intermediate drive rate positions and the highdrive rate position,

the controller including an electrical signal generator that drives thevalve system to move from the start position to the one or moreintermediate drive rate positions and to remain in the one or moreintermediate drive rate positions for one or more correspondingpredetermined amounts of time and further drives the valve system tomove from the one or more intermediate drive rate positions to the highdrive rate position on expiration of the one or more predeterminedamounts of time.

The positions of the valve system preferably each have a correspondingdegree of openness, the controller being adapted to generate anelectrical signal of selectable degree of output, the degree of opennessof the positions of the valve system being proportional to the degree ofoutput of the electrical signal generated by the controller.

The output of the electrical signal can one or more of electricalenergy, electrical power, voltage, current or amperage.

The degree of openness of the positions of the valve system each have acorresponding rate of flow of the drive fluid that is proportional tothe corresponding degree of openness of the positions of the valvesystem.

The tip end of the valve pin typically obstructs the gate to prevent themold material from flowing into the cavity in the first position, themold material flows at a maximum rate through the gate in the secondposition and the tip end of the valve pin restricts the flow of the moldmaterial to less than the maximum rate in the one or more intermediateupstream positions between the first position and the second position,and wherein

the valve pin is in one or more of the intermediate upstream positionswhen the valve system is in the one or more intermediate drive ratepositions.

The rate of travel of the actuator that corresponds to a highest of theone or more intermediate drive rate positions of the valve system isless than about 75% of the rate of travel of the actuator thatcorresponds to the high drive rate position of the valve system.

Each of the positions of the valve system preferably have acorresponding degree of openness, the actuator being driven at avelocity that is proportional to the degree of openness of the positionsof the valve system, the electrical signals generated by the controllereach having a degree of output that adjusts the valve system to a degreeof openness that is proportional to the degree of output of theelectrical signals.

The controller is programmable to automatically generate one or morefirst electrical signals having one or more corresponding first selecteddegrees of output that move the valve system to the one or moreintermediate drive rate positions to drive the actuator continuouslyupstream at one or more corresponding first velocities that are lessthan the maximum velocity, the controller generating a second electricalsignal on expiration of the one or more predetermined amounts of time,the second electrical signal having a second selected degree of outputthat moves the valve system to the high drive rate position to drive theactuator at the maximum velocity.

The controller typically includes electrical or electronic instructionsinterconnected to an electrical signal generator that automaticallyinstructs the electrical signal generator to generate the electricalsignals that drive the valve system to move from the start position tothe one or more intermediate drive positions and to remain in the one ormore intermediate drive positions for the one or more predeterminedamounts of time and further instructs the electrical signal generator togenerate an electrical signal that drives the valve system to move fromthe one or more intermediate drive positions to the high drive positionon expiration of the one or more predetermined amounts of time.

Each of the positions of the valve system have a corresponding degree ofopenness, the actuator being driven at a velocity that is proportionalto the degree of openness of the positions of the valve system, theelectrical signals generated by the controller each having a degree ofoutput that adjusts the valve system to a degree of openness that isproportional to the degree of output of the electrical signals.

The output of the electrical signal can be one or more of electricalenergy, electrical power, voltage, current or amperage.

Further in accordance with the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

an injection molding machine and a manifold that receives an injectedmold material from the injection molding machine, the manifold having adelivery channel that delivers the mold material under an injectionpressure to a first gate of a mold cavity,

an actuator interconnected to a valve pin driving the valve pin from afirst position where the tip end of the valve pin obstructs the gate toprevent the injection fluid material from flowing into the cavity,upstream to a second position upstream of the gate where the moldmaterial flows at a maximum rate through the gate and continuouslyupstream from the start position through one or more intermediatepositions between the first position and the second position wherein thetip end of the valve pin restricts flow of the mold material to one ormore corresponding rates of flow that are less than the maximum rate,

a valve system for controllably driving the valve pin, the valve systembeing controllably movable from a start position to one or moreintermediate drive rate positions and a high drive rate position, thehigh drive rate position driving the pin upstream at a high rate oftravel, the intermediate drive rate positions driving the pin upstreamat one or more intermediate rates of travel that are less than the highrate of travel,

the method comprising:

preselecting one or more lengths of time for the valve system to residein the one or more intermediate drive rate positions such that the tipend of the pin is disposed in a position that restricts the flow of moldmaterial through the gate to less than the maximum rate during theentirety of said preselected lengths of time,

beginning an injection cycle with the tip end of the valve pin in thefirst position and the valve system in the start position,

adjusting the valve system to operate at one or more of the intermediatedrive rate positions for the one or more selected lengths of time todrive the valve pin continuously upstream,

adjusting the valve system to operate at the high drive rate position todrive the tip end of the valve pin continuously upstream at the highrate of travel upon expiration of the one or more selected lengths oftime.

Such a method typically comprises carrying out the steps of beginningand adjusting automatically via an electrical controller havingprogrammable instructions.

In another aspect of the invention there is provided a method ofperforming an injection molding cycle in an injection molding apparatuscomprising:

an injection molding machine and a manifold that receives an injectedmold material from the injection molding machine, the manifold having adelivery channel that delivers the mold material under an injectionpressure to a first gate of a mold cavity,

an actuator interconnected to a valve pin driving the valve pin from afirst position where the tip end of the valve pin obstructs the gate toprevent the injection fluid material from flowing into the cavity,upstream to a second position upstream of the gate where the moldmaterial flows at a maximum rate through the gate and continuouslyupstream from the start position through one or more intermediatepositions between the first position and the second position wherein thetip end of the valve pin restricts flow of the injection fluid to one ormore rates less than the maximum rate,

a drive system for controllably driving the actuator and the valve pinupstream at one or more selected intermediate velocities and at one ormore high velocities that are higher than the intermediate velocities,

the method comprising:

selecting one or more lengths of time for the drive system to drive theactuator at the one or more intermediate velocities,

beginning an injection cycle with the tip end of the valve pin in thefirst position,

adjusting the drive system to drive the actuator at the one or moreintermediate velocities for the one or more selected lengths of time todrive the valve pin continuously upstream,

adjusting the drive system to drive the actuator at the one or more highvelocities to drive the tip end of the valve pin continuously upstreamat the one or more high velocities upon expiration of the one or moreselected lengths of time.

The drive system can be adjusted to drive the actuator at the one ormore intermediate velocities after the mold material has been injectedinto the cavity through another gate and has travelled through thecavity past the first gate.

The drive system can be adjusted to drive the actuator at a singleintermediate velocity for a single selected length of time.

The drive system can be interconnected to an electrical signalgenerating device operable to generate electrical signals ofcontrollably variable degree of output, the drive system beingadjustable in drive rate to adjust velocity to a degree that isproportional to the degree of output of the electrical signals, thesteps of adjusting the drive system comprising operating the electricalsignal generating device to generate electrical signals thatproportionally adjust the drive rate of the drive system according toelectrical signals having one or more selected degrees of output.

The length of travel between the first position and the one or moreintermediate positions along the drive path is between about 1 mm andabout 5 mm.

In another aspect of the invention there is provided an apparatus forcontrolling the rate of flow of mold material to a mold cavity, theapparatus comprising:

an injection molding machine and a manifold that receives the injectedmold material from the machine, the manifold having a delivery channelthat delivers the mold material at one or more flow rates through a gateto the mold cavity,

an actuator interconnected to a valve pin having a tip end, the actuatorbeing drivable to move the valve pin along a path of travel startingfrom a downstream gate closed position continuously upstream to andthrough a series of successively upstream intermediate upstream gateopen positions and further continuously upstream to a high upstream gateopen position,

a drive system connected to the actuator, the drive system being adaptedto drive the actuator continuously upstream beginning from the gateclosed position at one or more preselected intermediate velocities forone or more corresponding selected lengths of time and furthersubsequently driving the actuator continuously upstream at one or morehigh velocities that are higher than the intermediate velocities.

Such an apparatus typically further comprises

a controller interconnected to the drive system, the controller beingadapted to control operation of the drive system between the startposition, the one or more intermediate drive rate positions and the highdrive rate position,

the controller including an electrical signal generator that outputselectrical signals of controllably variable degree of output, the drivesystem being adjustable in drive rate to adjust velocity of the actuatorand the valve pin to a degree that is proportional to the degree ofoutput of the electrical signals,

the controller including instructions that operate the electrical signalgenerating device to generate electrical signals of one or morepreselected degrees of output that drive the actuator upstream atcorresponding ones of the intermediate upstream velocities for the oneor more corresponding selected lengths of time and that further drivethe actuator at the one or more high velocities on expiration of theselected lengths of time.

The output of the electrical signal can be one or more of electricalenergy, electrical power, voltage, current or amperage.

The tip end of the valve pin preferably obstructs the gate to preventthe mold material from flowing into the cavity when the actuator is inthe downstream gate closed position, the mold material flows at amaximum rate through the gate when the actuator is in the high upstreamgate open position and the tip end of the valve pin restricts the flowof the mold material to less than the maximum rate when the actuator isin the one or more intermediate upstream gate open positions, andwherein the valve pin is in one or more of the intermediate upstreampositions restricting flow of the mold material to less than the maximumrate when the drive system is driving the actuator at the one or moreintermediate velocities.

The rate of travel of the actuator when the actuator is driven at thehighest of the one or more intermediate velocities is less than about75% of the rate of travel of the actuator when the actuator is driven atthe lowest of the one or more high velocities.

The length of travel between the downstream gate closed position and thefurthest upstream of the one or more intermediate upstream gate openpositions is typically between about 1 mm and about 5 mm.

Further in accordance with the invention there is provided asequentially gated molding system comprising a mold having first andsecond gates leading to a common cavity and a manifold having first andsecond fluid flow channels respectively delivering a fluid mold materialthrough the first and second gates into the cavity, the systemcomprising:

a first valve controlling delivery of the fluid material through thefirst gate into the cavity beginning at a first time;

a second valve controlling delivery of the fluid material through thesecond gate beginning at a second time subsequent to the first time suchthat the fluid material has entered the cavity through the first gateand approached the second gate prior to the second time;

the second valve comprising an actuator interconnected to a valve pinhaving a tip end, the actuator moving the valve pin continuouslyupstream along a path of travel between a downstream gate closedposition and an intermediate upstream gate open position, the downstreamgate closed position being a position wherein the tip end of the valvepin obstructs the second gate to prevent fluid material from flowinginto the mold cavity, the intermediate upstream gate open position beinga predetermined position between the downstream gate closed position anda fully open, end of stroke position upstream of the intermediateupstream gate open position;

a controller interconnected to the actuator that controls movement ofthe actuator at least in part according to instructions that instructthe actuator to move the valve pin continuously upstream at one or moreselected velocities over the course of travel of the valve pin from thedownstream gate closed position to the intermediate upstream gate openposition.

In such an embodiment, the actuator can comprise an electrically drivenmotor interconnected to the valve pin that moves the valve pin at acontrollably variable rate according to an electrical or electronicsignal received from the controller that is controllably variable.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings in which:

FIG. 1 is a schematic cross-sectional side view of one embodiment of theinvention showing a mold having a valve with a gate injecting at acentral location in the cavity and a pair of lateral or distal valvesinjecting into the same cavity at lateral or distal locations, thecenter gate with center actuator 940 having been opened and shown closedsuch that a first shot of fluid material has entered the cavity andtraveled past the position of the lateral sequential gates, the lateralgates shown being open with their valve pin having traveled along anupstream restricted flow path RP allowing a second sequential shot offluid material to flow into and merge with the first shot of materialfrom the center gate within the cavity;

FIGS. 1A-1E are schematic cross-sectional close-up views of the centerand one of the lateral gates of the FIG. 1 apparatus showing variousstages of the progress of injection;

FIG. 2 is a schematic diagram of an embodiment of the invention showinggenerically a hydraulically actuated valve and its interconnection tothe hydraulic system and the control system for causing the valve pin towithdraw at the beginning of a cycle at predetermined reduced velocityfor a predetermined amount of time;

FIGS. 2A and 2B are schematic cross-sectional views of the hydraulicvalves and restrictors used in the system of FIG. 1 according to theinvention;

FIGS. 3A-3B show tapered end valve pin positions at various times andpositions between a starting closed position as in FIG. 3A and variousupstream opened positions, RP representing a selectable path length overwhich the velocity of withdrawal of the pin upstream from the gateclosed position to an open position is reduced (via a controllable flowrestrictor) relative to the velocity of upstream movement that the valvepin would normally have over the uncontrolled velocity path FOV when thehydraulic pressure is normally at full pressure and pin velocity is atits maximum;

FIGS. 4A-4B show a system having a valve pin that has a cylindricallyconfigured tip end, the tips ends of the pins being positioned atvarious times and positions between a starting closed position as inFIG. 4A and various upstream opened positions, RP wherein RP representsa path over which the velocity of withdrawal of the pin upstream fromthe gate closed position to an open position is reduced (via acontrollable flow restrictor or electric actuator) relative to thevelocity of upstream movement that the valve pin would normally haveover the uncontrolled velocity path FOV when the hydraulic pressure of ahydraulic actuator is normally at full pressure and pin velocity is atits maximum;

FIGS. 5A-5D are a series of plots of pin velocity versus time each plotrepresenting a different example of the opening of a gate lateral to acentral gate via continuous upstream withdrawal of a valve pin at onerate or set of rates over an initial flow path RP and at another higherrate or set of rates of upstream withdrawal of the valve pin beginningat a pin position of FOP and beyond when the fluid material flow istypically at a maximum unrestricted rate of flow through the open gatewithout any restriction or obstruction from the tip end of the pin.

DETAILED DESCRIPTION

FIG. 1 shows a system 10 with a central nozzle 22 feeding moltenmaterial from an injection molding machine through a main inlet 18 to adistribution channel 19 of a manifold 40. The distribution channel 19commonly feeds three separate nozzles 20, 22, 24 which all commonly feedinto a common cavity 30 of a mold 42. One of the nozzles 22 iscontrolled by actuator 940 and arranged so as to feed into cavity 30 atan entrance point or gate that is disposed at about the center 32 of thecavity. As shown, a pair of lateral nozzles 20, 24 feed into the cavity30 at gate locations that are distal 34, 36 to the center gate feedposition 32.

As shown in FIGS. 1, 1A the injection cycle is a cascade process whereinjection is effected in a sequence from the center nozzle 22 first andat a later predetermined time from the lateral nozzles 20, 24. As shownin FIG. 1A the injection cycle is started by first opening the pin 1040of the center nozzle 22 and allowing the fluid material 100 (typicallypolymer or plastic material) to flow up to a position 100 a in thecavity just before 100 b the distally disposed entrance into the cavity34, 36 of the gates of the lateral nozzles 24, 20 as shown in FIG. 1A.After an injection cycle is begun, the gate of the center injectionnozzle 22 and pin 1040 is typically left open only for so long as toallow the fluid material 100 b to travel to a position 100 p just pastthe positions 34, 36. Once the fluid material has travelled just past100 p of the lateral gate positions 34, 36, the center gate 32 of thecenter nozzle 22 is typically closed by pin 1040 as shown in FIGS. 1B,1C, 1D and 1E. The lateral gates 34, 36 are then opened by upstreamwithdrawal of lateral nozzle pins 1041, 1042 as shown in FIGS. 1B-1E. Asdescribed below, the rate of upstream withdrawal or travel velocity oflateral pins 1041, 1042 is controlled as described below.

In alternative embodiments, the center gate 32 and associated actuator940 and valve pin 1040 can remain open at, during and subsequent to thetimes that the lateral gates 34, 36 are opened such that fluid materialflows into cavity 30 through both the center gate 32 and one or both ofthe lateral gates 34, 36 simultaneously.

When the lateral gates 34, 36 are opened and fluid material NM isallowed to first enter the mold cavity into the stream 102 p that hasbeen injected from center nozzle 22 past gates 34, 36, the two streamsNM and 102 p mix with each other. If the velocity of the fluid materialNM is too high, such as often occurs when the flow velocity of injectionfluid material through gates 34, 36 is at maximum, a visible line ordefect in the mixing of the two streams 102 p and NM will appear in thefinal cooled molded product at the areas where gates 34, 36 inject intothe mold cavity. By injecting NM at a reduced flow rate for a relativelyshort period of time at the beginning when the gate 34, 36 is firstopened and following the time when NM first enters the flow stream 102p, the appearance of a visible line or defect in the final moldedproduct can be reduced or eliminated.

The rate or velocity of upstream withdrawal of pins 1041, 1042 startingfrom the closed position is controlled via controller 16, FIGS. 1, 2which controls the rate and direction of flow of hydraulic fluid fromthe drive system 700 to the actuators 940, 941, 942. A “controller,” asused herein, refers to electrical and electronic control apparati thatcomprise a single box or multiple boxes (typically interconnected andcommunicating with each other) that contain(s) all of the separateelectronic processing, memory and electrical signal generatingcomponents that are necessary or desirable for carrying out andconstructing the methods, functions and apparatuses described herein.Such electronic and electrical components include programs,microprocessors, computers, PID controllers, voltage regulators, currentregulators, circuit boards, motors, batteries and instructions forcontrolling any variable element discussed herein such as length oftime, degree of electrical signal output and the like. For example acomponent of a controller, as that term is used herein, includesprograms, controllers and the like that perform functions such asmonitoring, alerting and initiating an injection molding cycle includinga control device that is used as a standalone device for performingconventional functions such as signaling and instructing an individualinjection valve or a series of interdependent valves to start aninjection, namely move an actuator and associated valve pin from a gateclosed to a gate open position. In addition, although fluid drivenactuators are employed in typical or preferred embodiments of theinvention, actuators powered by an electric or electronic motor or drivesource can alternatively be used as the actuator component.

As shown in FIGS. 2A, 2B, a supply of hydraulic fluid 14 is fed firstthrough a directional control valve 750 mechanism that switches thehydraulic fluid flow to the actuator cylinders in either of twodirections: fluid out to withdraw the pin upstream, FIG. 2A, and fluidin to drive the pin downstream, FIG. 2B. At the beginning of aninjection cycle the gate of a lateral valve 34, 36 is closed and thehydraulic system is in the directional configuration of FIG. 2B. When acycle is started, the directional configuration of the directional valve750 of the hydraulic system 700 is switched by controller 16 to theconfiguration of FIG. 2A. The hydraulic system includes a flowrestriction valve 600 that can vary the rate of flow of hydraulic fluidto the actuator 941 under the control of the controller 16 to vary therate of travel, upstream or downstream of the piston of the actuator 941which in turn controls the direction and rate of travel of pin 1041.Although not shown in FIGS. 2A, 2B, the hydraulic system 700 controlsthe direction and rate of travel of the pistons of actuators 940 and 942in a manner similar to the manner of control of actuator 941 via theconnections shown in FIG. 1.

The user programs controller 16 via data inputs on a user interface toinstruct the hydraulic system 700 to drive pins 1041, 1042 at anupstream velocity of travel for a predetermined amount of time that isreduced relative to a maximum velocity that the hydraulic system candrive the pins 1041, 1042 to travel. As described below, such reducedpin withdrawal rate or velocity is executed for a preselected amount oftime that is less than the time of the entire injection cycle, thelatter part of the injection cycle being executed with the pins 1041,1042 being withdrawn at higher velocities. A typical amount of time overwhich the pins are instructed to withdraw at a reduced velocity isbetween about 0.25 and about 10 seconds, more typically between about0.5 and about 5 seconds, the entire injection cycle time typically beingbetween about 4 seconds and about 30 seconds, more typically betweenabout 6 seconds and about 12 seconds.

FIG. 1 shows position sensors 950, 951, 952 which sense the position ofthe actuator cylinders 940, 941, 942 and their associated valve pins(such as 1040, 1041, 1042) and feeds such position information tocontroller 16 for monitoring purposes. Such information may or may notbe used or included in conjunction with the apparatus and method of thepresent invention and is not a necessary component thereof given thatthe user selects and inputs time, and not position, to the controller 16as the essential variable for controlling drive of the valve pin 1040,1041, 1042 and actuator(s) 940-942 upstream at a selected less thanmaximum velocity.

As shown, fluid material 18 is injected from an injection machine into amanifold runner 19 and further downstream into the bores 44, 46 of thelateral nozzles 24, 22 and ultimately downstream through the gates 32,34, 36. When the pins 1041, 1042 are withdrawn upstream to a positionwhere the tip end of the pins 1041 are in a fully upstream open positionsuch as shown in FIG. 1D, the rate of flow of fluid material through thegates 34, 36 is at a maximum. However when the pins 1041, 1042 areinitially withdrawn beginning from the closed gate position, FIG. 1A, tointermediate upstream positions, FIGS. 1B, 1C, a gap 1154, 1156 thatrestricts the velocity of fluid material flow is formed between theouter surfaces 1155 of the tip end of the pins 44, 46 and the innersurfaces 1254, 1256 of the gate areas of the nozzles 24, 20. Therestricted flow gap 1154, 1156 remains small enough to restrict andreduce the rate of flow of fluid material 1153 through gates 34, 36 to arate that is less than maximum flow velocity over a travel distance RPof the tip end of the pins 1041, 1042 going from closed to upstream asshown in FIGS. 1, 1B, 1C, 1E and 3B, 4B.

The pins 1041 can be controllably withdrawn at one or more reducedvelocities (less than maximum) for one or more periods of time over theentirety of the length of the path RP over which flow of mold material1153 is restricted. Preferably the pins are withdrawn at a reducedvelocity over more than about 50% of RP and most preferably over morethan about 75% of the length RP. As described below with reference toFIGS. 3B, 4B, the pins 1041 can be withdrawn at a higher or maximumvelocity at the end COP2 of a less than complete restricted moldmaterial flow path RP2.

The trace or visible lines that appear in the body of a part that isultimately formed within the cavity of the mold on cooling above can bereduced or eliminated by reducing or controlling the velocity of the pin1041, 1042 opening or upstream withdrawal from the gate closed positionto a selected intermediate upstream gate open position that ispreferably 75% or more of the length of RP.

The periods of time over which the pins 1041, 1042 are withdrawn atreduced velocities are typically determined empirically by trial anderror runs. One or more, typically multiple, trial injection cycle runsare carried out to make specimen parts from the mold. Each trialinjection cycle run is carried out using a different period or periodsof time at which the pins 1041, 1042 are withdrawn at one or morereduced velocities over the trial period(s) of time, and the quality ofthe parts produced from all such trial runs are compared to determinethe optimum quality producing time(s) of reduced velocity pinwithdrawals. When the optimum time(s) have been determined, thecontroller is programmed to carry out an injection cycle where the pinwithdrawal velocities of pins 1041, 1042 are reduced for thepredetermined amounts of time at the predetermined reduced withdrawalrates.

RP can be about 1-8 mm in length and more typically about 2-6 mm andeven more typically 2-4 mm in length. As shown in FIG. 2 in such anembodiment, a control system or controller 16 is preprogrammed tocontrol the sequence and the rates of valve pin 1040, 1041, 1042 openingand closing. The controller 16 controls the rate of travel, namelyvelocity of upstream travel, of a valve pin 1041, 1042 from its gateclosed position for at least the predetermined amount of time that isselected to withdraw the pin at the selected reduced velocity rate.

The velocity of withdrawal of the valve pins 1041, 1042 is determined byregulation of the flow of hydraulic drive fluid that is pumped from asupply 14 to the actuators 941, 942 through a flow restrictor valve 600,FIGS. 1, 2, 2A, 2B. When the flow restrictor valve 600 is completelyopen, namely 100% open, allowing maximum flow of the pressurizedhydraulic fluid to the actuator cylinders, the valve pins 1041, 1042 aredriven at a maximum upstream travel velocity. According to theinvention, the degree of openness of the flow restrictor valve isadjusted for a select period of time beginning from the gate closedposition of the pin to less than 100% open. Adjustment of the flowrestrictor valve 600 to less than 100% open thus reduces the rate andvolume flow of pressurized hydraulic fluid to the actuator cylindersthus in turn reducing the velocity of upstream travel of the pins 1041,1042 for the selected period of time. At the end of the select period oftime of reduced openness of the valve 600, the valve 600 is opened toits 100% open position to allow the actuator pistons and the valve pins1041, 1042 to be driven at maximum upstream velocity in order to reducethe cycle time of the injection cycle.

The valve 600 typically comprises a restrictor valve that iscontrollably positionable anywhere between completely closed (0% open)and completely open (100% open). Adjustment of the position of therestrictor valve 600 is typically accomplished via a source ofelectrical power that controllably drives an electromechanical mechanism602 that causes the valve to rotate such as a rotating spool that reactsto a magnetic or electromagnetic field created by the electrical signaloutput of the controller 16, namely an output of electrical energy,electrical power, voltage, current or amperage the degree or amount ofwhich can be readily and controllably varied by conventional electricaloutput devices. The electro-mechanism 602 is controllably drivable tocause the valve 600 to open or close to a degree of openness that isproportional to the amount or degree of electrical energy that is inputto drive the electro-mechanism 602. The velocity of upstream withdrawaltravel of the pins 1041, 1042 are in turn proportional to the degree ofopenness of the valve 600. Thus the rate of upstream travel of the pins1041, 1042 is proportional to the amount or degree of electrical energythat is input to the electromechanism 602 that drives valves 600. Theelectromechanism 602 that is selected for driving the valve 600establishes in the first instance the maximum amount of electricalenergy or power (such as voltage or current) that is required to openthe valve to its 100% open position. A control for setting the amount ordegree of electrical energy or power input to the motor is containedwithin the controller 16. Controller 16 includes an interface thatenables the user to input any selected fraction or percentage of themaximum electrical energy or power needed to adjust the valve 600 toless than 100% open for any preselected amount of time beginning fromthe gate closed position of the valve pins 1041, 1042 and theirassociated actuators 941, 942. Thus the user selects a reduced upstreamvelocity of the pins 1041, 1042 by inputting to the controller 16 apercentage of the maximum amount of electrical energy or power input(voltage or current) needed to open the valve 600 to 100% open. The userinputs such selections into the controller 16. The user also selects theperiod of time over which the valve 600 is partially opened and inputssuch a selection into the controller 16. The controller 16 includesconventional programming or circuitry that receives and executes theuser inputs. The controller may include programming or circuitry thatenables the user to input as a variable a selected pin velocity ratherthan a percentage of electrical energy, the programming of thecontroller automatically converting the inputs by the user toappropriate instructions for reduced electrical input to theelectro-mechanism that that drives the valve 600.

Typically the user selects one or more reduced velocities that are lessthan about 90% of the maximum velocity (namely velocity when the valve600 is fully open), more typically less than about 75% of the maximumvelocity and even more typically less than about 50% of the maximumvelocity at which the pins 1041, 1042 are drivable by the hydraulicsystem. The actual maximum velocity at which the actuators 941, 942 andtheir associated pins 1041, 1042 are driven is predetermined byselection of the size and configuration of the actuators 941, 942, thesize and configuration of the restriction valve 600 and the degree ofpressurization and type of hydraulic drive fluid selected for use by theuser. The maximum drive rate of the hydraulic system is predetermined bythe manufacturer and the user of the system and is typically selectedaccording to the application, size and nature of the mold and theinjection molded part to be fabricated.

As shown by the series of examples of programs illustrated in FIGS.5A-5D one or more reduced pin velocities can be selected and the pindriven by restricted hydraulic fluid flow (or by reduced velocity driveby an electric actuator) for any one or more selected periods of timebetween the gate closed (X and Y axis zero position) and the finalintermediate upstream open gate position (4 mm for example in the FIG.5A example, 5 mm in the FIG. 5B example) at which point the pin 1041,1042 is driven to travel upstream at maximum upstream travel velocity(as shown, 100 mm/sec in the FIGS. 5A-5D examples). In the FIG. 5Aexample, the reduced pin velocity is selected as 50 mm/sec. In practicethe actual velocity of the pin may or may not be precisely known, the Yvelocity axis corresponding (and generally being proportional) to thedegree of electrical energy input to the motor that controls the openingof the flow restriction valve, 100 mm/sec corresponding to the valve 600being completely 100% open (and pin being driven at maximum velocity);and 50 mm/sec corresponding to 50% electrical energy input to theelectromechanism that drives the restriction valve 600 to one-half ofits maximum 100% degree of openness. In the FIG. 5A example, the timeover which the valve pin 1041, 1042 is programmed to travel at thereduced 50 mm/sec velocity is 0.08 seconds. Also in this example, thevalve pin 1041 travels to intermediate upstream gate open positionsbetween 0 mm (gate closed) and about 4 mm upstream at the reduced 50mm/sec velocity. After the pin 1041, 1042 has been driven for thepreselected 0.08 seconds (reaching an upstream position of about 4 mmfrom the gate closed position), the controller 16 instructs theelectro-mechanism that drives the valve 600 (typically a magnetic orelectromagnetic field driven device such as a spool) to open therestrictor valve 600 to full 100% open at which time the pin (and itsassociated actuator piston) are driven by the hydraulic system at themaximum travel rate 100 mm/sec for the predetermined, given pressurizedhydraulic system.

FIGS. 5B-5D illustrate a variety of alternative examples for driving thepin 1041, 1042 at reduced velocities for various durations of time. Forexample as shown in FIG. 5B, the pin is driven for 0.02 seconds at 25mm/sec, then for 0.06 seconds at 75 mm/sec and then allowed to go tofull valve open velocity shown as 100 mm/sec. Full valve open or maximumvelocity is typically determined by the nature of hydraulic (orpneumatic) valve or motor drive system that drives the valve pin. In thecase of a hydraulic (or pneumatic) system the maximum velocity that thesystem is capable of implementing is determined by the nature, designand size of the pumps, the fluid delivery channels, the actuator, thedrive fluid (liquid or gas), the restrictor valves and the like.

As shown in FIGS. 5A-5D, the velocity of the valve pin when the pinreaches the end of the reduced velocity period, the valve 600 can beinstructed to assume the full open position essentially instantaneouslyor alternatively can be instructed to take a more gradual approach up,between 0.08 and 0.12 seconds, to the maximum valve openness as shown inFIG. 5D. In all cases the controller 16 instructs the valve pin 1041,1042 to travel continuously upstream rather than follow a profile wherethe pin might travel in a downstream direction during the course of theinjection cycle. Most preferably, the actuator, valve pin, valves andfluid drive system are adapted to move the valve pin between a gateclosed position and a maximum upstream travel position that defines anend of stroke position for the actuator and the valve pin. Mostpreferably the valve pin is moved at the maximum velocity at one or moretimes or positions over the course of upstream travel of the valve pinpast the upstream gate open position. Alternatively to the hydraulicsystem depicted and described, a pneumatic or gas driven system can beused and implemented in the same manner as described above for ahydraulic system.

Preferably, the valve pin and the gate are configured or adapted tocooperate with each other to restrict and vary the rate of flow of fluidmaterial 1153, FIGS. 3A-3B, 4A-4B over the course of travel of the tipend of the valve pin through the restricted velocity path RP. Mosttypically as shown in FIGS. 3A, 3B the radial tip end surface 1155 ofthe end 1142 of pin 1041, 1042 is conical or tapered and the surface ofthe gate 1254 with which pin surface 1155 is intended to mate to closethe gate 34 is complementary in conical or taper configuration.Alternatively as shown in FIGS. 4A, 4B, the radial surface 1155 of thetip end 1142 of the pin 1041, 1042 can be cylindrical in configurationand the gate can have a complementary cylindrical surface 1254 withwhich the tip end surface 1155 mates to close the gate 34 when the pin1041 is in the downstream gate closed position. In any embodiment, theoutside radial surface 1155 of the tip end 1142 of the pin 1041 createsrestricted a restricted flow channel 1154 over the length of travel ofthe tip end 1142 through and along restricted flow path RP thatrestricts or reduces the volume or rate of flow of fluid material 1153relative to the rate of flow when the pin 1041, 1042 is at a full gateopen position, namely when the tip end 1142 of the pin 1041 hastravelled to or beyond the length of the restricted flow path RP (whichis, for example the 4 mm upstream travel position of FIGS. 5A-5C).

In one embodiment, as the tip end 1142 of the pin 1041 continues totravel upstream from the gate closed GC position (as shown for examplein FIGS. 3A, 4A) through the length of the RP path (namely the pathtravelled for the predetermined amount of time), the rate of materialfluid flow 1153 through restriction gap 1154 through the gate 34 intothe cavity 30 continues to increase from 0 at gate closed GC position toa maximum flow rate when the tip end 1142 of the pin reaches a positionFOP (full open position), FIGS. 5A-5D, where the pin is no longerrestricting flow of injection mold material through the gate. In such anembodiment, at the expiration of the predetermined amount of time whenthe pin tip 1142 reaches the FOP (full open) position FIGS. 5A, 5B, thepin 1041 is immediately driven by the hydraulic system at maximumvelocity FOV (full open velocity) typically such that the restrictionvalve 600 is opened to full 100% open.

In alternative embodiments, when the predetermined time for driving thepin at reduced velocity has expired and the tip 1142 has reached the endof restricted flow path RP2, the tip 1142 may not necessarily be in aposition where the fluid flow 1153 is not still being restricted. Insuch alternative embodiments, the fluid flow 1153 can still berestricted to less than maximum flow when the pin has reached thechangeover position COP2 where the pin 1041 is driven at a higher,typically maximum, upstream velocity FOV. In the alternative examplesshown in the FIG. 3B example when the predetermined time has expired fordriving the pin at reduced velocity and the tip end 1142 has reachedchangeover point COP, the tip end 1142 of the pin 1041 (and its radialsurface 1155) no longer restricts the rate of flow of fluid material1153 through the gap 1154 because the gap 1154 has increased to a sizethat no longer restricts fluid flow 1153 below the maximum flow rate ofmaterial 1153. Thus in one of the examples shown in FIG. 3B the maximumfluid flow rate for injection material 1153 is reached at the upstreamposition COP of the tip end 1142. In another example shown in FIG. 3B4B, the pin 1041 can be driven at a reduced velocity over a shorter pathRP2 that is less than the entire length of the restricted mold materialflow path RP and switched over at the end COP2 of the shorter restrictedpath RP2 to a higher or maximum velocity FOV. In the FIGS. 5A, 5Bexamples, the upstream FOP position is about 4 mm and 5 mm respectivelyupstream from the gate closed position. Other alternative upstream FOPpositions are shown in FIGS. 5C, 5D.

In another alternative embodiment, shown in FIG. 4B, the pin 1041 can bedriven and instructed to be driven at reduced or less than maximumvelocity over a longer path length RP3 having an upstream portion URwhere the flow of injection fluid mold material is not restricted butflows at a maximum rate through the gate 34 for the given injection moldsystem. In this FIG. 4B example the velocity or drive rate of the pin1041 is not changed over until the tip end of the pin 1041 or actuator941 has reached the changeover position COP3. As in other embodiments, aposition sensor senses either that the valve pin 1041 or an associatedcomponent has travelled the path length RP3 or reached the end COP3 ofthe selected path length and the controller receives and processes suchinformation and instructs the drive system to drive the pin 1041 at ahigher, typically maximum velocity upstream. In another alternativeembodiment, the pin 1041 can be driven at reduced or less than maximumvelocity throughout the entirety of the travel path of the pin during aninjection cycle from the gate closed position GC up to the end-of-strokeEOS position, the controller 16 being programmed to instruct the drivesystem for the actuator to be driven at one or more reduced velocitiesfor the time or path length of an entire closed GC to fully open EOScycle.

In the FIGS. 5A-5D examples, FOV is 100 mm/sec. Typically, when the timeperiod for driving the pin 1041 at reduced velocity has expired and thepin tip 1142 has reached the position COP, COP2, the restriction valve600 is opened to full 100% open velocity FOV position such that the pins1041, 1042 are driven at the maximum velocity or rate of travel that thehydraulic system is capable of driving the actuators 941, 942.Alternatively, the pins 1041, 1042 can be driven at a preselected FOVvelocity that is less than the maximum velocity at which the pin iscapable of being driven when the restriction valve 600 is fully open butis still greater than the selected reduced velocities that the pin isdriven over the course of the RP, RP2 path to the COP, COP2 position.

At the expiration of the predetermined reduced velocity drive time, thepins 1041, 1042 are typically driven further upstream past the COP, COP2position to a maximum end-of-stroke EOS position. The upstream COP, COP2position is downstream of the maximum upstream end-of-stroke EOS openposition of the tip end 1142 of the pin. The length of the path RP orRP2 is typically between about 2 and about 8 mm, more typically betweenabout 2 and about 6 mm and most typically between about 2 and about 4mm. In practice the maximum upstream (end of stroke) open position EOSof the pin 1041, 1042 ranges from about 8 mm to about 18 inches upstreamfrom the closed gate position GC.

The controller 16 includes a processor, memory, user interface andcircuitry and/or instructions that receive and execute the user inputsof percentage of maximum valve open or percentage of maximum voltage orcurrent input to the motor drive for opening and closing the restrictionvalve, time duration for driving the valve pin at the selected valveopenings and reduced velocities.

In alternative embodiments the controller can include a processor andinstructions that receive pin position information and signals from aposition sensor and calculate the real time velocity of the pin from thepin position data at one or more times or positions over the course ofthe pin travel through the RP, RP2, RP3 path length and/or beyond. Suchcalculations of velocity can be intermittent or continuous throughoutthe cycle. In such an embodiment, the calculated pin velocity isconstantly compared in real time to a predetermined target profile ofpin velocities over the predetermined time period for reduced velocityand the velocity of the pin is adjusted in real time by the controller16 to conform to the reduced velocity profile for the predeterminedamount of time. In this embodiment as in all previously describedembodiments, the pin is moved continuously upstream at all times betweenthe gate closed position and all positions upstream of the gate closedposition. Such control systems are described in greater detail in forexample U.S. Patent Publication no. 20090061034 the disclosure of whichis incorporated herein by reference.

As discussed above, control over the velocity of pin movement in anembodiment where the pin is driven by a hydraulic or pneumatic actuatoris typically accomplished by controlling the degree of openness of thefluid restriction valve 600, control over velocity and drive rate orposition of valve 600 being the same functions in terms of theinstructions, microprocessor design or computer software that carriesout instructing and implementing the velocity or drive rate adjustmentto the valve pin or actuator. Where the position sensing system sensesthe position of the pin or other component multiple times throughout thecourse of the pin or other component movement, and real time velocitycan be calculated by the controller 16, a program or instructions can bealternatively used to receive a velocity data input by the user to thecontroller 16 as the variable to be stored and processed instead of apredetermined voltage or current input Where an actuator that comprisesan electric motor is used as the drive mechanism for moving the valvepin 1041, 1042 instead of a fluid driven actuator, the controller 16 cansimilarly be programmed to receive and process velocity data input as avariable for controlling the velocity or rate of drive of the electricactuator.

1. A method of performing an injection molding cycle in an injectionmolding apparatus comprising: an injection molding machine and amanifold that receives an injected mold material from the injectionmolding machine, the manifold having a delivery channel that deliversthe mold material under an injection pressure to a first gate of a moldcavity, an actuator interconnected to a valve pin driving the valve pinfrom a first position where the tip end of the valve pin obstructs thegate to prevent the injection fluid material from flowing into thecavity, upstream to a second position upstream of the gate where themold material flows at a maximum rate through the gate and continuouslyupstream from the start position through one or more intermediatepositions between the first position and the second position wherein thetip end of the valve pin restricts flow of the injection mold materialto one or more rates less than the maximum rate, a valve system forcontrollably driving the valve pin, the valve system being controllablymovable from a start position to one or more intermediate drive ratepositions and a high drive rate position, the high drive rate positiondriving the pin upstream at a high rate of travel, the intermediatedrive rate positions driving the pin upstream at one or moreintermediate rates of travel that are less than the high rate of travel,the method comprising: selecting one or more lengths of time for thevalve system to operate or reside in corresponding ones of the one ormore intermediate drive rate positions, beginning an injection cyclewith the tip end of the valve pin in the first position and the valvesystem in the start position, adjusting the valve system to operate atthe one or more of the intermediate drive rate positions for the one ormore selected lengths of time to drive the valve pin continuouslyupstream.
 2. The method of claim 1 wherein the step of adjustingcomprises operating the valve system at one or more selectedintermediate drive rate positions for the length of an entire injectioncycle where the pin travels from the first position to an end of strokeposition with the valve system in one or more selected intermediatedrive rate positions.
 3. The method of claim 1 further comprisingadjusting the valve system to operate at the high drive rate position todrive the tip end of the valve pin continuously upstream at the highrate of travel upon expiration of the one or more selected lengths oftime.
 4. The method of claim 3 wherein the valve system is adjusted tooperate at the one or more intermediate drive rate positions after themold material has been injected into the cavity through another gate andhas travelled through the cavity past the first gate.
 5. The method ofclaim 3 wherein the valve system is adjusted to operate at a singleintermediate drive rate position for a single selected length of time.6. The method of claim 3 wherein the valve system is interconnected toan electrical signal generating device operable to generate electricalsignals of controllably variable output, the valve system beingadjustable in drive rate position to increase the flow of drive fluid toa degree that is proportional to the degree of output of the electricalsignals, the steps of adjusting the valve system comprising operatingthe electrical signal generating device to generate electrical signalsthat adjust the drive rate positions of the valve system accordingelectrical signals of selected degree of output.
 7. The method of claim3 wherein each of the drive rate positions of the valve system have adegree of openness, the drive fluid of the valve system driving theactuator and the valve pin at a rate that is proportional to the degreeof openness of the positions of the valve system, the one or moreintermediate drive rate positions having a degree of openness that isless than the degree of openness of the high drive rate flow position.8. The method of claim 3 wherein the length of travel between the firstposition and the one or more intermediate positions along the drive pathis between about 1 mm and about 5 mm.
 9. An apparatus for controllingthe rate of flow of mold material to a mold cavity, the apparatuscomprising: an injection molding machine and a manifold that receivesthe injected mold material from the machine, the manifold having adelivery channel that delivers the mold material at one or more flowrates through a gate to the mold cavity, an actuator interconnected to avalve pin having a tip end, the actuator being drivable to move thevalve pin along a path of travel starting from a downstream gate closedposition continuously upstream to and through a series of successivelyupstream intermediate upstream gate open positions and furthercontinuously upstream to a high upstream gate open position, a valvesystem in fluid communication with the actuator to drive the actuatorwith drive fluid at one or more rates of travel, the valve system havinga start position, one or more intermediate drive rate positions and ahigh drive rate position, the start position holding the valve pin inthe gate closed position, the high drive rate position driving theactuator upstream at a maximum velocity under which the valve system iscapable of driving the actuator, the one or more intermediate drive ratepositions driving the actuator upstream at one or more correspondingvelocities that are less than the maximum velocity, a controllerinterconnected to the valve system, the controller being adapted tocontrol movement of the valve system between the start position, the oneor more intermediate drive rate positions and the high drive rateposition, the controller including an electrical signal generator thatdrives the valve system to move from the start position to the one ormore intermediate drive rate positions and to remain in the one or moreintermediate drive rate positions for one or more correspondingpredetermined amounts of time and further drives the valve system tomove from the one or more intermediate drive rate positions to the highdrive rate position on expiration of the one or more predeterminedamounts of time.
 10. The apparatus of claim 9 wherein the positions ofthe valve system each have a corresponding degree of openness, thecontroller being adapted to generate an electrical signal of selectabledegree of output, the degree of openness of the positions of the valvesystem being proportional to the degree of output of the electricalsignal generated by the controller.
 11. The apparatus of claim 10wherein the output of the electrical signal is one or more of electricalenergy, electrical power, voltage, current or amperage.
 12. Theapparatus of claim 10 wherein the degree of openness of the positions ofthe valve system each have a corresponding rate of flow of the drivefluid that is proportional to the corresponding degree of openness ofthe positions of the valve system.
 13. The apparatus of claim 10 whereinthe tip end of the valve pin obstructs the gate to prevent the moldmaterial from flowing into the cavity in the first position, the moldmaterial flows at a maximum rate through the gate in the second positionand the tip end of the valve pin restricts the flow of the mold materialto less than the maximum rate in the one or more intermediate upstreampositions between the first position and the second position, andwherein the valve pin is in one or more of the intermediate upstreampositions when the valve system is in the one or more intermediate driverate positions.
 14. The apparatus of claim 9 wherein the rate of travelof the actuator that corresponds to a highest of the one or moreintermediate drive rate positions of the valve system is less than about75% of the rate of travel of the actuator that corresponds to the highdrive rate position of the valve system.
 15. The apparatus of claim 9wherein each of the positions of the valve system have a correspondingdegree of openness, the actuator being driven at a velocity that isproportional to the degree of openness of the positions of the valvesystem, the electrical signals generated by the controller each having adegree of output that adjusts the valve system to a degree of opennessthat is proportional to the degree of output of the electrical signals.16. The apparatus of claim 15 wherein the controller is programmable toautomatically generate one or more first electrical signals having oneor more corresponding first selected degrees of output that move thevalve system to the one or more intermediate drive rate positions todrive the actuator continuously upstream at one or more correspondingfirst velocities that are less than the maximum velocity, the controllergenerating a second electrical signal on expiration of the one or morepredetermined amounts of time, the second electrical signal having asecond selected degree of output that moves the valve system to the highdrive rate position to drive the actuator at the maximum velocity. 17.The apparatus of claim 9 wherein the controller includes electrical orelectronic instructions interconnected to an electrical signal generatorthat automatically instructs the electrical signal generator to generatethe electrical signals that drive the valve system to move from thestart position to the one or more intermediate drive positions and toremain in the one or more intermediate drive positions for the one ormore predetermined amounts of time and further instructs the electricalsignal generator to generate an electrical signal that drives the valvesystem to move from the one or more intermediate drive positions to thehigh drive position on expiration of the one or more predeterminedamounts of time.
 18. The apparatus of claim 17 wherein each of thepositions of the valve system have a corresponding degree of openness,the actuator being driven at a velocity that is proportional to thedegree of openness of the positions of the valve system, the electricalsignals generated by the controller each having a degree of output thatadjusts the valve system to a degree of openness that is proportional tothe degree of output of the electrical signals.
 19. The apparatus ofclaim 18 wherein the output of the electrical signal is one or more ofelectrical energy, electrical power, voltage, current or amperage.
 20. Amethod of performing an injection molding cycle in an injection moldingapparatus comprising: an injection molding machine and a manifold thatreceives an injected mold material from the injection molding machine,the manifold having a delivery channel that delivers the mold materialunder an injection pressure to a first gate of a mold cavity, anactuator interconnected to a valve pin driving the valve pin from afirst position where the tip end of the valve pin obstructs the gate toprevent the injection fluid material from flowing into the cavity,upstream to a second position upstream of the gate where the moldmaterial flows at a maximum rate through the gate and continuouslyupstream from the start position through one or more intermediatepositions between the first position and the second position wherein thetip end of the valve pin restricts flow of the mold material to one ormore corresponding rates of flow that are less than the maximum rate, avalve system for controllably driving the valve pin, the valve systembeing controllably movable from a start position to one or moreintermediate drive rate positions and a high drive rate position, thehigh drive rate position driving the pin upstream at a high rate oftravel, the intermediate drive rate positions driving the pin upstreamat one or more intermediate rates of travel that are less than the highrate of travel, the method comprising: preselecting one or more lengthsof time for the valve system to reside in the one or more intermediatedrive rate positions such that the tip end of the pin is disposed in aposition that restricts the flow of mold material through the gate toless than the maximum rate during the entirety of said preselectedlengths of time, beginning an injection cycle with the tip end of thevalve pin in the first position and the valve system in the startposition, adjusting the valve system to operate at one or more of theintermediate drive rate positions for the one or more selected lengthsof time to drive the valve pin continuously upstream, adjusting thevalve system to operate at the high drive rate position to drive the tipend of the valve pin continuously upstream at the high rate of travelupon expiration of the one or more selected lengths of time.
 21. Themethod of claim 20 further comprising carrying out the steps ofbeginning and adjusting automatically via an electrical controllerhaving programmable instructions.
 22. A method of performing aninjection molding cycle in an injection molding apparatus comprising: aninjection molding machine and a manifold that receives an injected moldmaterial from the injection molding machine, the manifold having adelivery channel that delivers the mold material under an injectionpressure to a first gate of a mold cavity, an actuator interconnected toa valve pin driving the valve pin from a first position where the tipend of the valve pin obstructs the gate to prevent the injection fluidmaterial from flowing into the cavity, upstream to a second positionupstream of the gate where the mold material flows at a maximum ratethrough the gate and continuously upstream from the start positionthrough one or more intermediate positions between the first positionand the second position wherein the tip end of the valve pin restrictsflow of the injection fluid to one or more rates less than the maximumrate, a drive system for controllably driving the actuator and the valvepin upstream at one or more selected intermediate velocities and at oneor more high velocities that are higher than the intermediatevelocities, the method comprising: selecting one or more lengths of timefor the drive system to drive the actuator at the one or moreintermediate velocities, beginning an injection cycle with the tip endof the valve pin in the first position, adjusting the drive system todrive the actuator at the one or more intermediate velocities for theone or more selected lengths of time to drive the valve pin continuouslyupstream, adjusting the drive system to drive the actuator at the one ormore high velocities to drive the tip end of the valve pin continuouslyupstream at the one or more high velocities upon expiration of the oneor more selected lengths of time.
 23. The method of claim 22 wherein thedrive system is adjusted to drive the actuator at the one or moreintermediate velocities after the mold material has been injected intothe cavity through another gate and has travelled through the cavitypast the first gate.
 24. The method of claim 22 wherein the drive systemis adjusted to drive the actuator at a single intermediate velocity fora single selected length of time.
 25. The method of claim 22 wherein thedrive system is interconnected to an electrical signal generating deviceoperable to generate electrical signals of controllably variable degreeof output, the drive system being adjustable in drive rate to adjustvelocity to a degree that is proportional to the degree of output of theelectrical signals, the steps of adjusting the drive system comprisingoperating the electrical signal generating device to generate electricalsignals that proportionally adjust the drive rate of the drive systemaccording to electrical signals having one or more selected degrees ofoutput.
 26. The method of claim 22 wherein the length of travel betweenthe first position and the one or more intermediate positions along thedrive path is between about 1 mm and about 5 mm.
 27. An apparatus forcontrolling the rate of flow of mold material to a mold cavity, theapparatus comprising: an injection molding machine and a manifold thatreceives the injected mold material from the machine, the manifoldhaving a delivery channel that delivers the mold material at one or moreflow rates through a gate to the mold cavity, an actuator interconnectedto a valve pin having a tip end, the actuator being drivable to move thevalve pin along a path of travel starting from a downstream gate closedposition continuously upstream to and through a series of successivelyupstream intermediate upstream gate open positions and furthercontinuously upstream to a high upstream gate open position, a drivesystem connected to the actuator, the drive system being adapted todrive the actuator continuously upstream beginning from the gate closedposition at one or more preselected intermediate velocities for one ormore corresponding selected lengths of time and further subsequentlydriving the actuator continuously upstream at one or more highvelocities that are higher than the intermediate velocities.
 28. Theapparatus of claim 27 further comprising a controller interconnected tothe drive system, the controller being adapted to control operation ofthe drive system between the start position, the one or moreintermediate drive rate positions and the high drive rate position, thecontroller including an electrical signal generator that outputselectrical signals of controllably variable degree of output, the drivesystem being adjustable in drive rate to adjust velocity of the actuatorand the valve pin to a degree that is proportional to the degree ofoutput of the electrical signals, the controller including instructionsthat operate the electrical signal generating device to generateelectrical signals of one or more preselected degrees of output thatdrive the actuator upstream at corresponding ones of the intermediateupstream velocities for the one or more corresponding selected lengthsof time and that further drive the actuator at the one or more highvelocities on expiration of the selected lengths of time.
 29. Theapparatus of claim 28 wherein the output of the electrical signal is oneor more of electrical energy, electrical power, voltage, current oramperage.
 30. The apparatus of claim 28 wherein the tip end of the valvepin obstructs the gate to prevent the mold material from flowing intothe cavity when the actuator is in the downstream gate closed position,the mold material flows at a maximum rate through the gate when theactuator is in the high upstream gate open position and the tip end ofthe valve pin restricts the flow of the mold material to less than themaximum rate when the actuator is in the one or more intermediateupstream gate open positions, and wherein the valve pin is in one ormore of the intermediate upstream positions restricting flow of the moldmaterial to less than the maximum rate when the drive system is drivingthe actuator at the one or more intermediate velocities.
 31. Theapparatus of claim 28 wherein the rate of travel of the actuator whenthe actuator is driven at the highest of the one or more intermediatevelocities is less than about 75% of the rate of travel of the actuatorwhen the actuator is driven at the lowest of the one or more highvelocities.
 32. The apparatus of claim 30 wherein the length of travelbetween the downstream gate closed position and the furthest upstream ofthe one or more intermediate upstream gate open positions is betweenabout 1 mm and about 5 mm.
 33. A sequentially gated molding systemcomprising a mold having first and second gates leading to a commoncavity and a manifold having first and second fluid flow channelsrespectively delivering a fluid mold material through the first andsecond gates into the cavity, the system comprising: a first valvecontrolling delivery of the fluid material through the first gate intothe cavity beginning at a first time; a second valve controllingdelivery of the fluid material through the second gate beginning at asecond time subsequent to the first time such that the fluid materialhas entered the cavity through the first gate and approached the secondgate prior to the second time; the second valve comprising an actuatorinterconnected to a valve pin having a tip end, the actuator moving thevalve pin continuously upstream along a path of travel between adownstream gate closed position and an intermediate upstream gate openposition, the downstream gate closed position being a position whereinthe tip end of the valve pin obstructs the second gate to prevent fluidmaterial from flowing into the mold cavity, the intermediate upstreamgate open position being a predetermined position between the downstreamgate closed position and a fully open, end of stroke position upstreamof the intermediate upstream gate open position; a controllerinterconnected to the actuator that controls movement of the actuator atleast in part according to instructions that instruct the actuator tomove the valve pin continuously upstream at one or more selectedvelocities over the course of travel of the valve pin from thedownstream gate closed position to the intermediate upstream gate openposition.